The use of hydraulic pumps, such as power steering pumps, is well known in the automotive industry. Power steering systems use pumps to provide hydraulic fluid to the steering system. Conventional hydraulic pumps are typically positive displacement pumps, such as vane pumps. The operational performance of the power steering system is dependent on a reliable and consistent flow output from these pumps.
The reliability and consistency of flow through hydraulic pumps is affected by cavitation of the fluid passing through the pump. Cavitation can cause undesired noise and erosive wear of the pump. It can also cause pump failure.
Current design solutions to counter cavitation include feeding fluid from multiple sides of the pump, using several staged pumps, or using cams to reduce flow into the pump. These solutions have significant disadvantages when viewed in conjunction with the tight packaging conditions presented in modern vehicle design. Current designs require more space or specialized packaging designs that are often not available.
Therefore, there is a need for a design that is effective in reducing cavitation, and the noise and adverse affects associated with it, while at the same time minimizing packaging requirements.